A method and apparatus of the present invention improves hearing for a hearing impaired person by introducing and maintaining a mechanical feedback barrier between a microphone and a transducer of an implantable hearing assistance system. In this method, mechanical sound vibrations impinging on the person""s body habitus are received with an electromechanical device (e.g. microphone) disposed at a body habitus sound reception site. The body habitus sound reception site can be located within the external auditory canal, or external of the external auditory canal either subdermally or external of the scalp, or even subdermally along the external auditory canal.
The mechanical sound vibrations are converted with the electromechanical device to an amplified electrical signal. Next, the amplified electrical signal is delivered to the inner ear with a transducer operatively coupled between the electromechanical device and the middle ear or the inner ear.
Finally, a mechanical feedback barrier is introduced and maintained between the sound reception site and the transducer to minimize acoustic feedback therebetween. Preferably, this feedback barrier is established by removing a portion of the hearing impaired person""s ossicular chain (e.g malleus, incus, or stapes) or fixing a portion of the ossicular chain to prevent transmission of sound feedback. In other embodiments, a portion of the ossicular chain is not removed but merely separated so that the procedure can be reversed if desired at a later time.
This method and apparatus of the present invention optimizes hearing improvement by preventing unnecessary mechanical feedback that can occur through the ossicular chain and the external auditory canal. Interrupting the ossicular chain, or otherwise immobilizing the ossicular chain, to prevent this retrograde sound transmission permits significant enhancement of the gain applied to the amplified electrical signal transmitted to the stapes or inner ear. In addition, less mechanical energy is required to transmit the acoustic energy to the interrupted ossicular chain or cochlea than when the ossicular chain remains intact. Accordingly, this method and apparatus reduces power consumption and frequent battery replacement for implantable hearing assistance systems.